One of the properties required for silver halide color photographic materials (hereinafter simply referred- to as "light-sensitive material" as necessary) is color reproductivity.
One approach for improving color reproducibility is to use colored couplers in, e.g., color negative light-sensitive materials for picture taking, to correct for undesired absorption of colored dye images. These colored couplers are disclosed in many publications and patents, for instance Research Disclosure No. 17643, VII-G.
Colored couplers used for the correction of undesired absorption of cyan images include those which exhibit a maximum absorption wavelength between about 500 nm and 600 nm in the visible light range and undergo a coupling reaction with an oxidation product of an aromatic primary amine developing agent to form a cyan dye image which exhibits a maximum absorption wavelength between about 630 nm and 750 nm.
However, a cyan dye image also has an absorption in the visible light range of 400 to 500 nm. If these undesired absorptions are also corrected for by the so-called yellow-colored cyan couplers, an effect which photographically approximates the interimage effect developed from a cyan colored image layer and a yellow colored image layer can be obtained, probably providing an advantage in color reproduction. This possibility is described in JP-A-61-221748 and JP-A-319774 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
On the other hand, it has been keenly demanded in the art to speed up photographic processing, i.e., to reduce the requisite time of processing. In particular, reduction in desilvering time, which accounts for almost half of the total processing time, has been an important subject of study.
Known means for speeding up desilvering include the use of a bleach-fix monobath containing an aminopolycarboxylic acid iron (II) complex salt and a thiosulfate, as disclosed in German Patent 866,605. However, since the aminopolycarboxylic acid iron (II) complex salt, which essentially has weak oxidizing power (bleaching power), is combined with a thiosulfate having reducing power, such bleach-fix baths have considerably reduced bleaching power and are of no practical use, particularly for high sensitivity and high silver content color light-sensitive materials for photographing. The bleach-fix monobaths have great difficulty in achieving sufficient desilvering.
In order to improve bleaching power, it has been proposed to add various bleaching accelerators to the bleach bath, the bleach-fix bath or a respective prebath thereof. Bleaching accelerators so far proposed include various mercapto compounds described, e.g., in U.S. Pat. No. 3,893,858, British Patent 1,138,842, and JP-A-53-141623; compounds having a disulfide linkage as described in JP-A-53-95630; thiazolidine derivatives as described in JP-B-53-9854 (the term "JP-B" as used herein means an "examined published Japanese patent application"); isothiourea derivatives as described in JP-A-53-94927; thiourea derivatives as described in JP-B-45-8506 and JP-B-49-26586; thioamide compounds as described in JP-A-49-42349; dithiocarbamic acid salts as described in JP-A-55-26506; and arylenediamine compounds as described in U.S. Pat. No. 4,552,834.
Although some of these known bleaching accelerators exhibit bleaching accelerating effects, they still involve problems which render them unsatisfactory for practical use. For example, some are expensive; some have poor stability in the bath having bleaching ability; and some have insufficient bleaching accelerating effects.
Further, where a bleaching accelerator having a mercapto group is added to any of the bleaching bath, the bleach-fix bath, or a respective prebath thereof, cases often arise in which the mercapto compound reacts with undeveloped silver halide in an emulsion layer or with silver halide formed by the bleaching reaction, resulting in the formation of a sparingly insoluble silver salt, which is not solubilized by the fixing agent and causes insufficient fixing.
In addition, where continuous processing is performed with replenishment using a processing bath having bleach-fixing ability, silver ions accumulate in the bleach-fix bath. The accumulated silver ions form a sparingly soluble silver salt with the above-described mercapto compound, which cannot be solubilized by a fixing agent, especially when the rate of replenishment is reduced, thus worsening the state of fixing.
Hence, use of a bleaching accelerator in the bleach bath, the bleach-fix bath or a respective prebath thereof is subject to various restrictions.
It is also known to incorporate the above-mentioned mercapto-containing bleaching accelerator or a precursor thereof into the light-sensitive material. However, this technique also involves problems. For example, the mercapto compound present in the light-sensitive material not only has considerable influence on photographic properties, but it also forms a sparingly soluble salt with the silver halide in the undeveloped area of the light-sensitive material.
On the other hand, disclosures of couplers capable of releasing a bleaching accelerator are found in Research Disclosure, Item 24241, ibid., Item 11449, and JP-A-61-201247.
Although these bleaching accelerator-releasing couplers bring about some improvement in the abovementioned problems, they are still unsatisfactory in bleaching or desilvering effect, particularly in rapid processing in which the processing time of desilvering after color development is reduced, giving rise to a problem of unsatisfactory color reproduction. Moreover, when processing is carried out rapidly and continuously at a low rate of replenishment, the desilvering properties are deteriorated, making these couplers impractical.